Hi there. First time poster long time programmer. I have a site that is hosted by DIscountASP which sends out emails on a daily basis to our registered users. I am tech support for my Business Team and they have indicated to me that lately, quite a few of the emails that our site has been trying to send out has been blocked. Here is a sample response we've been getting: "Subject: Undelivered Mail Returned to Sender This is the mail system at host mc1.internetmailserver.net. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system <[email protected]>: host cloud1.spamtitan.com[96.127.141.203] said: 554 5.7.1 Service unavailable; Client host [64.79.170.98] blocked using sip.invaluement.local (in reply to RCPT TO command)" First some backgroud: 1. This is a custom developed ASP site whose original vendor devleoper is no longer reachable. 2. The original support resource left with little to no notice and this was dropped into my lap with no transition or documentation. 3. I can pretty much reverse engineer anything if there is source code available but have never developed/deployed/maintained an ASP site. Now, back to the issue: Our outgoing email is obviously being blocked as spam but what I'm trying to figure out is where the SMTP is configured on a DiscountASP hosted site. In the sites's code, the SMTP host is simply coded as "localhost" -- with some vauge comments about how that was changed based on some posting on a DiscountASP article but I dont know where. There is no code for port, user or password authentication of any kind. In fact, our sending email code looks a lot like what is shown on this Support page: https://support.discountasp.net/kb/a364/how-to-send-email-in-asp_net.aspx Also note that NOT all of our outgoing emails are blocked -- just a few. I have also checked and confirmed that the "TO" email addresses are valid. Some Questions: 1. Who or what is "localhost"? 2. Where is the email actually being sent from? 3. Is mail being sent from a DiscountASP server? Any advice? Thanks, Manny
localhost is the web server relay for mail (or, in general, for connections between any two servers on the internal network). One of our email gateways, separate from the web server. Yes. internetmailserver.net is the domain used for our email servers. If the blocks were due to one of our mail servers being blacklisted (which does happen from time to time), all of your messages would be blocked. At least temporarily, until we cleared up the blacklisting. The fact that it's only some messages leads me to believe it's the message content. Automated emails from something like a forum or a blog are often subject to being classified as spam, and either outright rejected or sent to the end user's spam or junk folders. That's kind of an ongoing problem for a lot of those kinds of automated messages. The only thing I could suggest is editing that content to make it read a bit less like an automated message (that's worked for me in the past), but other than that it's a tough problem to solve. Every receiving mail server has different rules for what it considers to be spam, so it's difficult to insure 100% delivery of any email.
